<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- 表单标签 -->
    <form action="">
        <!-- 普通单行输入框 -->
        <input type="text">
        <input type="password">
        <input type="radio" name="a">
        <input type="radio" name="a">
        <input type="checkbox">
        <!-- 下拉菜单 -->
        <select>
            <option value="">1</option>
            <option value="">2</option>
        </select>
        <!-- 多行文本输入框：文本域 -->
        <textarea></textarea>
        <!-- 按钮 -->
        <button type="button">按钮</button>
    </form>
</body>
</html>